FORT LAUDERDALE FLA. — FORT LAUDERDALE, Fla. -- The girl retches, writhes, yowls and bares her teeth. "Get outta here, me not wanna leave," she shrieks at the priest, as one hand snaps the gauze bonds tying her to the chair.

No, it's not a rerun of "The Exorcist." It's a segment on "20/20" to be aired tonight that shows an actual Roman Catholic ritual of casting out demons. And, except for the lack of levitation and white-face, the exorcism closely resembles the 1973 movie starring Linda Blair.

Videotaped at a nun's home in suburban Palm Beach County last October, the segment shows perhaps the only church-authorized recording of the Rite of Exorcism. The affected girl, referred to only as Gina, thrashes under the effect of ancient prayers, sprinkled holy water and a cross pressed to her head.

Many Americans believe in the devil. In a 1990 Gallup Poll, 55 percent of the respondents said they believed in the devil, and 49 percent said they believe that people are sometimes possessed by the devil. In a 1984 poll by Louis Harris and Associates, 25 percent said they believed in the power of exorcism.

Yet most Catholic leaders say possession is rare. "I've heard of only a handful of exorcisms in the last 40 years," says the Rev. Kenneth Doyle, communications director for the National Conference of Catholic Bishops. "The church always looks first for natural medical or psychological explanations."

And when churchmen do perform an exorcism, they almost never talk about it. The main exorcist in the "20/20" report is known only as "Father A.," and his face is obscured.

In the film, the priests say the girl is controlled by 10 evil spirits. They meet her violent reactions by doggedly following the prayers and gestures of the rite. The ordeal takes about six hours.

"It's a terrifying experience at times," Father A. confesses beforehand.

PTC ABC reporter Tom Jarriel treats the subject with respect, if a bit too much credulity. But there is the obligatory Jesuit skeptic, in this case psychiatrist James Gill, who thinks the placebo effect is at work here. If the girl believes in the exorcism, he says, then it worked.

Also quoted is Dr. Warren Schlanger of Miami Children's Hospital, where Gina was treated before and after the exorcism. He doesn't believe in demons, but notes that her condition improved slightly afterward.